1. Field of the Invention
The present invention relates to a disposable tree syringe for injecting liquid agents into the living tissue of a tree trunk.
2. Description of the Prior Art
Tree injection is an highly preferred method of introducing agents into trees. When a tree is sprayed with a treatment agent, only a very small portion of that treatment agent is absorbed by the tree while the remaining portion of the treatment agent is lost to the environment. When a tree is injected with a treatment agent, almost all of the injected agent is taken up by the tree and almost none of the treatment agent is lost to the environment. Consequently, tree injection is an highly efficient and environmentally safe means of introducing treatment agents into the living tissues of trees.
Tree injection can presently be accomplished with reusable tree injection systems and disposable tree syringes. Reusable tree injection systems have typically been complicated and costly apparatuses requiring extensive cleaning between uses. However, reusable tree injecting apparatuses can be used an indefinite number of times. Disposable tree syringes offer convenience and ease of use and can be used by one who is not inclined to invest in a tree injection system. Since disposable tree syringes can only be used for one injection, and since disposable tree syringes might be used by those who only occasionally perform tree injections, a successful tree syringe should be simple, inexpensive and easy to use.
A disposable tree syringe that is simple, inexpensive and easy to use has long been sought after in the prior art. U.S. Pat. No. 3,286,401 by Mauget discloses a telescoping tree syringe comprising a vertical, double walled container portion which receives a single walled cap portion. At the bottom of Mauget's double walled container portion is an horizontal passageway blocked by a gate member which is adapted to resist internal pressure. To use Mauget's syringe, a feeder tube is first inserted into an hole that is drilled into living tree tissue. The assembled container and cap containing a liquid agent is then compressed. Mauget's container and cap have features that lock them together when compressed. The compressed Mauget syringe is then engaged with the feeder tube so that the feeder tube forces open the gate member. The pressurized liquid agent in the Mauget syringe then escapes through the feeder tube and into the living tissue of the tree. Lenardson in U.S. Pat. No. 4,365,440 improves Mauget's syringe by adding circumferencial features such as grooves and ridges to the cap and container walls so that the cap and container engage and seal as they are pushed together.
An example of another type of disposable tree syringe is described and claimed by DeVliegert in U.S. Pat. No. 4,989,366. DeVliegert's syringe has a lower housing, a middle housing and an upper housing. DeVliegert's lower housing has a central, axial drain tube that is closed off from the interior of the lower housing by a thin membrane. The upper housing of DeVliegert's syringe has a cap portion and a cylendrical wall that telescopes inside the middle housing. A rubber ring seal is placed between corresponding radial end flanges extending from the middle and upper housings. The rubber seal provides an air tight seal between the upper and middle housings. DeVliegert's syringe is assembled for use by partially filling the combined middle and upper housings with a liquid agent and then gluing the middle housing to the lower housing. DeVliegert's syringe has a spike fixed to the inside wall of the upper housing cap that is adapted to break the thin membrane in the lower housing when the upper housing is pushed down into the middle housing.
The prior art tree syringes developed by Mauget and DeVliegert are admirable devices which allow the efficient and environmentally safe treatment of trees with liquid agents. However, these prior art tree syringes include several components and can be difficult to use. DeVliegert's tree syringe uses four parts which must be glued together and assembled before the syringe can be used. The Mauget type tree syringe has a separate feeder tube. Both Mauget's and DeVliegert's tree syringes are configured so that if a leak develops between the mating portions of the syringe, potentially toxic liquid agent can spray back in the direction of the operator. Accordingly, there still exists a need for a simpler, less expensive, disposable tree syringe that is comprised of only two parts, that is easy to use and that will, if it leaks, eject liquid agent away from the operator.